In the past, when a patient on a rehabilitation bed attempted to rise up from the bed, stand up on the floor and attempt to start walking, he could not put his feet on the floor without first shifting his waist toward the bed side. Especially to a patient in need of rehabilitation, such a waist shift motion was a heavy burden and, in addition, any conventional bed was very inconvenient for bowel evacuation.
To solve these problems, some improved types of beds were offered. Such beds were designed to partially sink down, enabling the patient to rise to a sit-down position without the waist shift motion and then stand up at the sink position or evacuate the bowel at the sit-down position. However, even the improved types do not suffice for walk training because the level gap between the sink position and the floor impeded efforts of the patient to walk and further the sink part of the bed was not easy for the trainee to walk on stably.